In conventional fracturing of wells, proppant and fracturing fluid are mixed in a blender and then pumped into a well. As a consequence, the blender, pump and lines carrying the fracturing fluid downstream of the blender are subject to wear from the proppant, which is frequently highly abrasive material such as sand. In addition, any flow meters or other apparatus in the lines are subject to wear and possible wash out due to the proppant. Such wear may result in failure of the equipment, or leaks that may be hazardous. The potential for wear and the possibility of fire resulting from a leak makes it necessary to inspect equipment regularly.
In addition, when proppant is mixed with fracturing fluid in a blender the proppant may clump together and it is difficult to ensure uniform mixing of the proppant in the fracturing fluid. Since fracturing operations are carried out very quickly, there is little time to rectify an error in proppant concentration, with the result that too little or too much proppant may be injected into the formation at a critical part of the fracturing operation. This may ruin the fracturing operation, or require it to be repeated, in the case that is feasible.